Tag: Astronomy Picture of the Day

Astronomy Picture of the Day – The Black Eye Galaxy

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

 M64: The Black Eye Galaxy
Image Credit & Copyright: Michael Miller, Jimmy Walker

Explanation: This big, bright, beautiful spiral galaxy is Messier 64, often called the Black Eye Galaxy or the Sleeping Beauty Galaxy for its heavy-lidded appearance in telescopic views. M64 is about 17 million light-years distant in the otherwise well-groomed northern constellation Coma Berenices. In fact, the Red Eye Galaxy might also be an appropriate moniker in this colorful composition. The enormous dust clouds obscuring the near-side of M64’s central region are laced with the telltale reddish glow of hydrogen associated with star forming regions. But they are not this galaxy’s only peculiar feature. Observations show that M64 is actually composed of two concentric, counter-rotating systems. While all the stars in M64 rotate in the same direction as the interstellar gas in the galaxy’s central region, gas in the outer regions, extending to about 40,000 light-years, rotates in the opposite direction. The dusty eye and bizarre rotation are likely the result of a billion year old merger of two different galaxies.

 

Astronomy Picture of the Day – The Medusa Nebula

Astronomy Picture of the Day

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2015 June 17

The Medusa Nebula
Image Credit & Copyright: European Southern Observatory, VLT

 

Explanation: Braided, serpentine filaments of glowing gas suggest this nebula’s popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old planetary nebula some 1,500 light-years away along the southern border of the constellation Gemini. Like its mythological namesake, the nebula is associated with a dramatic transformation. The planetary nebula phase represents a final stage in the evolution of low mass stars like the sun, as they transform themselves from red giants to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet radiation from the hot star powers the nebular glow. An unrelated, bright, foreground star is near center in this close-up, telescopic view, while the Medusa’s transforming central star is actually the dimmer star below center and toward the right-hand part of the frame. The Medusa Nebula is estimated to be over 4 light-years across.

Astronomy Picture of the Day – Auroras and Star Trails over Iceland

Astronomy Picture of the Day

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2015 June 16

Auroras and Star Trails over Iceland
Image Credit & Copyright: Vincent Brady

 

Explanation: It was one of the quietest nights of aurora in weeks. Even so, in northern- Iceland during last November, faint auroras lit up the sky every clear night. The featured 360-degree panorama is the digital fusion of four wide-angle cameras each simultaneously taking 101 shots over 42 minutes. In the foreground is serene Lake Myvatn dotted with picturesque rock formations left over from ancient lava flows. Low green auroras sweep across the sky above showing impressive complexity near the horizon. Stars far in the distance appear to show unusual trails — as the Earth turned — because early exposures were artificially faded.

Astronomy Picture of the Day – A Colorful Lunar Corona

Astronomy Picture of the Day

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2015 June 15

A Colorful Lunar Corona
Image Credit & Copyright: Sergio Montúfar

 

Explanation: What are those colorful rings around the Moon? A corona. Rings like this will sometimes appear when the Moon is seen through thin clouds. The effect is created by the quantum mechanical diffraction of light around individual, similarly-sized water droplets in an intervening but mostly-transparent cloud. Since light of different colors has different wavelengths, each color diffracts differently. Lunar Coronae are one of the few quantum mechanical color effects that can be easily seen with the unaided eye. The featured lunar corona was captured around a Strawberry Moon on June 2 from La Plata, Argentina. Similar coronae that form around the Sun are typically harder to see because of the Sun’s great brightness.

Astronomy Picture of the Day – Intergalactic Wanderer

Astronomy Picture of the Day

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2015 June 4

NGC 2419 – Intergalactic Wanderer
Image Credit & Copyright: Bob Franke

 

Explanation: Three objects stand out in this thoughtful telescopic image, a view toward the mostly stealthy constellation Lynx. The two brightest (the spiky ones) are nearby stars. The third is the remote globular star cluster NGC 2419, at distance of nearly 300,000 light-years. NGC 2419 is sometimes called “the Intergalactic Wanderer”, an appropriate title considering that the distance to the Milky Way’s satellite galaxy, the Large Magellanic Cloud, is only about 160,000 light-years. Roughly similar to other large globular star clusters like Omega Centauri, NGC 2419 is itself intrinsically bright, but appears faint because it is so far away. NGC 2419 may really have an extragalactic origin as, for example, the remains of a small galaxy captured and disrupted by the Milky Way. But its extreme distance makes it difficult to study and compare its properties with other globular clusters that roam the halo of our Milky Way galaxy.

Astronomy Picture of the Day – Supernova and the Unexpected Universe

Astronomy Picture of the Day

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2015 May 31

Supernova 1994D and the Unexpected Universe
Image Credit: High-Z Supernova Search Team, HST, NASA

 

Explanation: Long ago, far away, a star exploded. Supernova 1994D, visible as the bright spot on the lower left, occurred in the outskirts of disk galaxy NGC 4526. Supernova 1994D was not of interest for how different it was, but rather for how similar it was to other supernovae. In fact, the light emitted during the weeks after its explosion caused it to be given the familiar designation of a Type Ia supernova. If all Type 1a supernovae have the same intrinsic brightness, then the dimmer a supernova appears, the farther away it must be. By calibrating a precise brightness-distance relation, astronomers are able to estimate not only the expansion rate of the universe (parameterized by the Hubble Constant), but also the geometry of the universe we live in (parameterized by Omega and Lambda). The large number and great distances to supernovae measured over the past few years, when combined with other observations, are interpreted as indicating that we live in a previously unexpected universe.

Astronomy Picture of the Day – Saturn at Opposition

Astronomy Picture of the Day

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2015 May 29

Saturn at Opposition
Image Credit & Copyright: Christopher Go

Explanation: Telescopic observers on Earth have been treated to spectacular views of Saturn lately as the ringed planet reached its 2015 opposition on May 23 at 0200 UT. Of course opposition means opposite the Sun in Earth’s sky. So near opposition Saturn is up all night, at its closest and brightest for the year. These sharp images taken within hours of the Sun-Earth-Saturn alignment also show the strong brightening of Saturn’s rings known as the opposition surge or the Seeliger Effect. Directly illuminated, the ring’s icy particles cast no shadows and strongly backscatter sunlight toward planet Earth, creating the dramatic surge in brightness. Saturn currently stands in the sky not far from bright Antares, alpha star of the constellation Scorpius.

Astronomy Picture of the Day – Dwarf Planet, Bright Spot

Astronomy Picture of the Day

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2015 May 14

Dwarf Planet, Bright Spot
Image Credit: NASA, JPL-Caltech, UCLA, MPS/DLR/IDA

Explanation: Now at Ceres, Dawn’s camera recorded this closer view of the dwarf planet’s northern hemisphere and one of its mysterious bright spots on May 4. A sunlit portrait of a small, dark world about 950 kilometers in diameter, the image is part of a planned sequence taken from the solar-powered spacecraft’s 15-day long RC3 mapping orbit at a distance of 13,600 kilometers (8,400 miles). The animated sequence shows Ceres’ rotation, its north pole at the top of the frame. Imaged by Hubble in 2004 and then by Dawn as it approached Ceres in 2015, the bright spot itself is revealed to be made up of smaller spots of reflective material that could be exposed ice glinting in the sunlight. On Saturday, Dawn’s ion propulsion system was turned on to spiral the spacecraft into a closer 4,350-kilometer orbit by June 6. Of course another unexplored dwarf planet, Pluto, is expecting the arrival of a visitor from Earth, the New Horizons spacecraft, by mid-July.

Astronomy Picture of the Day – Meteor in the Milky Way

Astronomy Picture of the Day

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Meteor in the Milky Way
Image Credit & Copyright: Marko Korosec

Explanation: Earth’s April showers include the Lyrid Meteor Shower, observed for more than 2,000 years when the planet makes its annual passage through the dust stream of long-period Comet Thatcher. A grain of that comet’s dust, moving 48 kilometers per second at an altitude of 100 kilometers or so, is swept up in this night sky view from the early hours of April 21. Flashing toward the southeastern horizon, the meteor’s brilliant streak crosses the central region of the rising Milky Way. Its trail points back toward the shower’s radiant in the constellation Lyra, high in the northern springtime sky and off the top of the frame. The yellowish hue of giant star Antares shines to the right of the Milky Way’s bulge. Higher still is bright planet Saturn, near the right edge. Seen from Istra, Croatia, the Lyrid meteor’s greenish glow reflects in the waters of the Adriatic Sea.

Astronomy Picture of the Day – An Unexpected Aurora over Norway

Astronomy Picture of the Day

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2015 May 4


An Unexpected Aurora over Norway
Image Credit & Copyright: Tommy Richardsen

Explanation: Sometimes the sky lights up unexpectedly. A trip to northern Norway to photograph auroras was not going as well as hoped. It was now past midnight in Steinsvik, Troms, in northern Norway, and the date was 2014 February 8. Despite recent activity on the Sun, the skies were disappointing. Therefore, the astrophotographer began packing up to go. His brother began searching for a missing lens cap. When the sky suddenly exploded with spectacular aurora. Reacting quickly, a sequence detailing dramatic green curtains was captured, with the bright Moon near the image center, and the lens-cap seeking brother on the far right. The auroral flare lasted only a few minutes, but the memory of this event, the photographer speculates, will last much longer.

Astronomy Picture of the Day – MESSENGER’s Last Day on Mercury

Astronomy Picture of the Day

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2015 May 1


MESSENGER’s Last Day on Mercury
Image Credit: NASA, Johns Hopkins Univ. APL, Arizona State Univ., CIW

 

Explanation: The first to orbit Mercury, the MESSENGER spacecraft came to rest on this region of Mercury’s surface yesterday. Constructed from MESSENGER image and laser altimeter data, the scene looks north over the northeastern rim of the broad, lava filled Shakespeare basin. The large, 48 kilometer (30 mile) wide crater Janacek is near the upper left edge. Terrain height is color coded with red regions about 3 kilometers above blue ones. MESSENGER’S final orbit was predicted to end near the center, with the spacecraft impacting the surface at nearly 4 kilometers per second (over 8,700 miles per hour) and creating a new crater about 16 meters (52 feet) in diameter. The impact on the far side of Mercury was not observed by telescopes, but confirmed when no signal was detected from the spacecraft given time to emerge from behind the planet. Launched in 2004, the MErcury Surface, Space ENvironment, GEochemisty and Ranging spacecraft completed over 4,000 orbits after reaching the Solar System’s innermost planet in 2011.

Astronomy Picture of the Day – The Flame Nebula in Visible and Infrared

Astronomy Picture of the Day

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The Flame Nebula in Visible and Infrared 
Image Credit & Copyright: Optical (RGB+Ha): Aldo Mottino & Ezequiel Bellocchio (Argentina); Infrared: ESO/J. Emerson/VISTA.

 

Explanation: What lights up the Flame Nebula? Fifteen hundred light years away towards the constellation of Orion lies a nebula which, from its glow and dark dust lanes, appears, on the left, like a billowing fire. But fire, the rapid acquisition of oxygen, is not what makes this Flame glow. Rather the bright star Alnitak, the easternmost star in the Belt of Orion visible just to the right of the nebula, shines energetic light into the Flame that knocks electrons away from the great clouds of hydrogen gas that reside there. Much of the glow results when the electrons and ionized hydrogen recombine. The above false-color picture of the Flame Nebula (NGC 2024) was taken is a composite of both visible and infrared light, the later energy band being where a young star cluster becomes visible. The Flame Nebula is part of the Orion Molecular Cloud Complex, a star-forming region that includes the famous Horsehead Nebula.

Astronomy Picture of the Day – Blue Tears and the Milky Way

Astronomy Picture of the Day

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2015 April 24


Blue Tears and the Milky Way
Image Credit & Copyright: Rogelio Bernal Andreo (Deep Sky Colors)

 

Explanation: Lapping at rocks along the shore of the Island of Nangan, Taiwan, planet Earth, waves are infused with a subtle blue light in this sea and night skyscape. Composed of a series of long exposures made on April 16 the image captures the faint glow from Noctiluca scintillans. Also known as sea sparkles or blue tears, the marine plankton’s bioluminescence is stimulated by wave motion. City lights along the coast of mainland China shine beneath low clouds in the west but stars and the faint Milky Way still fill the night above. Over the horizon the galaxy’s central bulge and dark rifts seem to echo the rocks and luminous waves.

Astronomy Picture of the Day – Colorful Star Clouds in Cygnus

Astronomy Picture of the Day

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2015 April 22


Colorful Star Clouds in Cygnus
Image Credit & Copyright: André van der Hoeven

 

Explanation: Stars can form in colorful surroundings. Featured here is a star forming region rich in glowing gas and dark dust toward the constellation of the Swan (Cygnus), near the bright star Sadr. This region, which spans about 50 light years, is part of the Gamma Cygni nebula which lies about 1,800 light years distant. Toward the right of the image is Barnard 344, a dark and twisted dust cloud rich in cool molecular gas. A dramatic wall of dust and red-glowing hydrogen gas forms a line down the picture center. While the glowing red gas is indicative of small emission nebulas, the blue tinted areas are reflection nebulas — starlight reflecting from usually dark dust grains. The Gamma Cygni nebula will likely not last the next billion years, as most of the bright young stars will explode, most of the dust will be destroyed, and most of the gas will drift away.

Astronomy Picture of the Day – Total Solar Eclipse over Svalbard

Astronomy Picture of the Day

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2015 April 20

Total Solar Eclipse over Svalbard
Image Credit & Copyright: Thanakrit Santikunaporn

 

Explanation: Going, going, gone. That was the feeling in Svalbard, Norway last month during a total eclipse of the Sun by the Moon. In the featured image, the eclipse was captured every three minutes and then digitally merged with a foreground frame taken from the same location. Visible in the foreground are numerous gawking eclipse seekers, some deploying pretty sophisticated cameras. As the Moon and Sun moved together across the sky — nearly horizontally from this far north — an increasing fraction of the Sun appears covered by the Moon. In the central frame, the Moon’s complete blockage of the disk of the Sun makes the immediate surroundings appear like night during the day. The exception is the Moon itself, which now appears surrounded by the expansive corona of the Sun. Of course, about 2.5 minutes later, the surface of the Sun began to reappear. The next total eclipse of the Sun will occur in 2016 March and be visible from Southeast Asia.

Astronomy Picture of the Day for April 10th – Mars, Ceres, Vesta

Astronomy Picture of the Day

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2014 April 10

 Mars, Ceres, Vesta
Image Credit & Copyright: Tunç Tezel (TWAN)

Explanation: That bright, ruddy star you’ve recently noticed rising just after sunset isn’t a star at all. That’s Mars, the Red Planet. Mars is now near its 2014 opposition (April 8) and closest approach (April 14), looping through the constellation Virgo opposite the Sun in planet Earth’s sky. Clearly outshining bluish Spica, alpha star of Virgo, Mars is centered in this labeled skyview from early April, that includes two other solar system worlds approaching their opposition. On the left, small and faint asteroid Vesta and dwarf planet Ceres are seen near star Tau Virginis. But you’ll just have to imagine NASA’s Dawn spacecraft cruising between the small worlds. Having left Vesta in September of 2012, Dawn’s ion engine has been steadily driving it to match orbits with Ceres, scheduled to arrive there in February 2015. Of course, you can also look near Mars for the Moon opposite the Sun in Earth’s sky on the night of April 14/15 … and see a total lunar eclipse.

Astronomy Picture of the Day – Teimareh Petroglyphs and Star Trails

Astronomy Picture of the Day

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2012 July 12

Teimareh Petroglyphs and Star Trails  

Image Credit & Copyright: Babak Tafreshi (TWAN)

Explanation: Engraved in rock, these ancient petroglyphs are abundant in the Teimareh valley, located in the Zagros Mountains of central Iran. They likely tell a tale of hunters and animals found in the middle eastern valley 6,000 years ago or more, etched by artists in a prehistoric age. In the night sky above are star trails etched by the rotation of planet Earth during the long composite exposure made with a modern digital camera. On the left, the center of the star trail arcs is the North Celestial Pole (NCP), the extension of Earth’s axis into space, with Polaris, the North Star, leaving the bright, short, stubby trail closest to the NCP. But when these petroglyphs were carved, Polaris would have made a long arc through the night. Since the Earth’s rotation axis precesses like a wobbling top, 6,000 years ago the NCP was near the border of the constellations Draco and Ursa Major, some 30 degrees from its current location in planet Earth’s sky.

Astronomy Picture of the Day – A Morning Line of Stars and Planets

Astronomy Picture of the Day

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2012 July 11

 A Morning Line of Stars and Planets

 Image Credit & Copyright: Yuri Beletsky (Las Campanas Observatory,  Carnegie Institution for Science)

Explanation: Early morning dog walkers got a visual treat last week  as bright stars and planets appeared to line up. Pictured above, easily visible from left to right, were the  Pleiades open star cluster,  Jupiter,  Venus, and the  “Follower” star  Aldebaran, all seen before a starry background. The image was taken from the  Atacama desert in western  South America.  The glow of the rising Sun can be seen over the eastern horizon. Jupiter and Venus will  continue to dazzle pre-dawn strollers all over planet Earth  for the rest of the month,  although even now the  morning planets are seen projected away from the line connecting their distant stellar  sky mates.

Astronomy Picture of the Day – Volcano and Aurora in Iceland

Astronomy Picture of the Day

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Volcano and Aurora in Iceland  

Image Credit & Copyright: Sigurdur H. Stefnisson

 

 Explanation: Sometimes both heaven and Earth erupt.   In  Iceland in 1991, the  volcano Hekla erupted at the same time that  auroras were visible overhead.   Hekla, one of the most  famous volcanoes in the world, has  erupted at least 20 times over the   past millennium,  sometimes causing  great destruction.   The last eruption occurred only twelve years ago but caused only minor  damage.   The green auroral band occurred fortuitously about 100 kilometers above the erupting  lava.   Is Earth the Solar System’s only planet with both auroras and volcanos?

Astronomy Picture of the Day for June 14

Astronomy Picture of the Day

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2012 June 14

M13: The Great Globular Cluster in Hercules

Image Credit & Copyright: Martin Pugh  

 

 

Explanation: In 1716, English astronomer Edmond Halley noted, “This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent.” Of course, M13 is now modestly recognized as the Great Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Telescopic views reveal the spectacular cluster’s hundreds of thousands of stars. At a distance of 25,000 light-years, the cluster stars crowd into a region 150 light-years in diameter, but approaching the cluster core upwards of 100 stars could be contained in a cube just 3 light-years on a side. For comparison, the closest star to the Sun is over 4 light-years away. Along with the cluster’s dense core, the outer reaches of M13 are highlighted in this sharp color image. The cluster’s evolved red and blue giant stars show up in yellowish and blue tints.